Long-Term Building Air Measurements
for Volatile Organic Compounds (VOCs) including Aldehydes
California Department of Health Services
In, the State Legislature directed the Department of General Services (DGS) to incorporate sustainable practices in the design and construction of a 1.5 million ft2 of the Capitol Area East End Complex (CAEEC). To address the Legislatures directive, a multi-agency team, known as the Green Team, was formed under the leadership of the Secretary of the State and Consumer Services Agency and, in partnership with the Department of Health Services, California Integrated Waste Management Board, California Energy Commission, California Air Resources Board, and Department of Water Resources worked with DGS to develop sustainable criteria for the CAEEC. These criteria, among others, included several to ensure good indoor air quality, including setting target limits on chemical emissions from interior finishing building materials and conducting airborne contaminant testing after completion of the construction and prior to occupancy. Two design/build teams were selected: one for Building 225 and another for the remaining four buildings (171, 172, 173,174). The design/build teams were responsible for the design of the buildings (the basic shell design had been done previously by the State) and the construction.
In order to ascertain the post-occupancy indoor air quality of a sustainable complex such as the CAEEC and to find out how it performs over time, the concentrations of Volatile Organic Compounds (VOCs) and aldehydes were measured along with local and building ventilation rates. Based on the measured VOC concentrations and ventilation rates, emissions from building materials and occupant activities to the indoor environment (such as cleaning products and perfumes) could be identified and their temporal changes could be studied. It is noted that due to the narrow scope of this study, other important aspects of indoor environmental quality, such as semi-volatile organic compounds, or noise and lighting were not studied. The specific goals of this research study were to:
1. Measure VOC including aldehyde concentrations periodically during and after occupancy of the five buildings for at least 12 months after occupancy. Compare measured concentrations to those referenced in: (a) Section 1350 as issued for the project and in its most current version; and (b) U.S. EPAs indoor air quality database of 100 randomly-selected office buildings known as the Building Assessement Survey and Evaluation (BASE) study.
2. Study temporal changes of measured concentrations to determine the effect of building materials, office furniture, occupant activities, and cleaning/maintenance products on indoor air quality.
3. Determine whether or not emissions of target chemicals in the indoor environment can be calculated reasonably well using emission data from small chamber tests.
Compare the occupant survey results for Blocks 225
and 172 collected by Center for the Built Environment (CBE) at
5. Discuss the lessons learned that can be used in future projects.
2. Eight building- and occupant-related chemicals were identified to determine the effect of building materials, office furniture, occupant activities, and cleaning/maintenance products on indoor air quality. The five building- related chemicals are: acetaldehyde, caprolactam, formaldehyde, naphthalene, and nonanal; the three occupant-related chemicals include: benzaldehyde, d-5 and d-limonene. However, very few chemicals could be traced to a unique source. Only one building-related compound (caprolactam) and one occupant-related compound (d-5) were clearly identifiable from unique sources. In the case of caprolactam, there was a clear decrease over time in the emissions of this chemical and in the case of d-5, there was a clearly identifiable increase over time in the emissions of this chemical. Emission factors of some of the other target chemicals (i.e., acetaldehyde, benzaldehyde, naphthalene, d-limonene, and nonanal) fluctuated throughout the study.
Post-occupancy local emission factors of some of these eight chemicals were fairly uniform within each building, whereas, others differed substantially from building median values. Chemicals with highly variable local emission factors were: d-5 (occupant-related), d-limonene (cleaning-related), caprolactam (variable only in certain sampling scenarios this chemical is emitted by carpeting and variability was presumably due to hallway carpet replacement), and formaldehyde (variability was presumably due to local generation of this chemical from cleaning and other activities).
a. Lack of data on cleaning and maintenance activities, touch up or other introduction of building materials, and furnishings, or finishes after the initial occupancy. Collection of emissions data from cleaning and maintenance products was beyond the scope of this study, but would have been useful to have had collected these data.
b. Variations of building ventilation rates and local ventilation rates. Despite the efforts to provide consistently the same amount of ventilation from one sampling session to the next by setting the ventilation systems to provide their minimum design outdoor airflows, variations of building ventilation rates and local ventilation rates occurred from one sampling session to the next, necessitating ventilation measurements during each sampling scenario.
c. Emissions testing of building material samples by their manufacturer does not necessarily guarantee that materials of similar chemical profile would be delivered and installed in a building. Despite the fact that the office furniture systems for the entire complex were tested to the States IAQ emissions specifications, there were substantial differences in the formaldehyde concentrations of two buildings (172 and 225) and those of the other three buildings in which systems furniture was supplied by a different vendor.
d. Accurate characterization of indoor air chemical concentrations requires numerous samples and ventilation measurements at several locations over an extended period of time. Many variables need to be considered and controlled in the building, or accounted for in the data analysis.
e. Analytical procedure variations need to be accounted for when air sampling in buildings is conducted to determine whether concentration target limits have been met. It is important that duplicate samples are collected at each site and samples with variability above a pre-determined threshold be discarded.
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